Abstract: The static strength and stability of a derrick structure (78.5m high) after its members
removed partly are researched. The derrick is modeled by three-dimensional spatial beam elements
based on ANSYS. By the static analysis, the strength of the derrick after its member removing
partly is larger than that of the original derrick structure since some loads disappear. From the
buckling analysis, it can be found that the stability reduces drastically when removing some
Abstract: Ti2SnC dispersion-strengthened (DS) copper matrix composites were prepared by
hot-pressing method. The changes of mechanical properties of the composites as a function of
microstructure were studied. The results demonstrated that the grain size of Cu decreased
pronouncedly by incorporating of Ti2SnC, and the strengthening effect was significant. The addition
of 5 vol.% Ti2SnC particles to Cu resulted in a near five-fold increase in the yield strength and the
tensile strength also increased by 188 MPa. The magnitude of the increase was a function of the
change of the microstructure.
Abstract: In present paper effect of alloying elements and strengthening particle on the impact
toughness were investigated. Load and energy in the impact tests were also discussed in detail for
Ti-2Al, Ti-2Sn,Ti-2Zr, Ti-1Mo and Ti/TiC. Impact tests were carried out at room temperature (293K)
and low temperature (83K) using a 300J capacity impact machine. Ti-1Mo, Ti-2Zr,Ti-2Sn alloys
exhibit high impact toughness even at low temperature, while Ti-2Al and Ti/TiC only have high
toughness at room temperature. At room temperature, general yielding occurred in all the materials,
but it occurred only in Ti-1Mo, Ti-2Zr and Ti-2Sn at low temperature. It seemed that strengthening
titanium couldn’t affect the elastic energy (Ei) effectively, but bring about more changes to Ep
(propagation energy of crack) than to Ei (initiation energy of crack). As for the effect of alloying
elements on the impact toughness, it seems to be related to the comprehensive result of the
concentration and electronegative property of alloying elements. The interface between the TiC
particles and matrix resulted in low toughness, especially at cryogenic temperature.
Abstract: A parameterized 3-D finite element model of the screw conveyor of a decanter centrifuge
was established. With the model, stress analyses for the screw conveyor under normal operation
conditions were carried out and the influences of the structural parameters were investigated.
Orthogonal designs were used to sort out major factors and optimize calculations for the effects of
factors on the strength of the conveyor. With the finite element calculation results, four empirical
formulas for the strength of the conveyor under different loadings were regressed. By applying stress
superposition principle, strength check criteria under normal operation conditions were given which
can be used for the design of the screw conveyor.
Abstract: The paper experimentally investigated the change of LF9 properties, including strength at
room temperature and 350°C, plasticity and impact toughness, under various heat treatment
schedules. Results show that the strength of LF9 decreases and plasticity and toughness increase
after secondary aging, with the increase of solid solution temperature. Meanwhile, with the increase
of aging time, the strength of LF9 increase and plasticity and toughness decrease. The investigation
of optical metallography, TEM and phase analysis indicate that the phenomena are mainly caused
by the precipitation of η, γ’and γ’’.
Abstract: The creep behavior of functionally graded material under in-plane bending moment is
investigated in this paper. By extending the classic beam theory an analytical model is proposed to
predict the distributions of creep strain and creep stress inside the functionally graded material
according to the relationship between the inclusion volume fraction and composite creep coefficient.
The analytical solution agrees well with the results obtained by the finite element method and the
basic knowledge about time-dependent behavior of functionally graded material is achieved to guide
its design and fabrication.
Abstract: The surface of K24 superalloy was processed with laser cladding & LSP (laser shock
processing). Residual stress in the laser cladding zone by LSP was measured with X-ray stress tester
X-350A, and the variational rule of residual stress in the cladding zone by tempering treatment of 8
hours and 16 hours was measured, respectively. The experimental results show that compressive
residual stress of K24 superalloy surface by laser cladding & laser shock processing is above
-600MPa, which exceeds residual stress by mechanical peening treatment; and there is no clear effect
on residual stress by tempering treatment at 600°C for 8 hours and 16 hours, respectively, which can
improve fatigue life of K24 superalloy.
Abstract: Large scale Ni-based alloy sheets are prepared by electron beam physical vapor deposition
with and without tungsten added into melting pools respectively. Addition W increased vapor rate and
decreased compositional transformation during deposition. Chemical constitution of the sheet
prepared through tungsten is more similar to that of the ingot. Microstructure of two alloy sheets is
observed by scanning electron microscope (SEM) and atom force microscope (AFM). The results
show that both of the sheets consist of columnar grains, whose major axes are almost parallel to the
normal direction of the sheet. However, the average diameter of grains of the sheet through tungsten is
larger than that of the sheet not through tungsten in minor axis direction. Mechanical properties and
failure mechanisms of both sheets are studied. Tensile tests are conducted on a number of specimens.
Strength, strain-to-failure are estimated under loading condition. The results show that the sheet
prepared by EB-PVD through tungsten has a superior strength and an elongation percentage than that
of the one prepared without tungsten.
Abstract: In order to validate a procedure for creep rupture tests using small punch specimens, the
influences of oxidation on the creep deflection curve, rupture time and ductility of miniature
specimens were investigated. Using disc test specimens of 10mm in diameter and 0.5mm in thickness,
a variety of small punch creep (SPC) tests for Cr5Mo steel at the condition of 550°C-404N and
650°C-189N under the protection of different Argon flow and in air atmosphere were firstly carried
out. Metallographic observations, micro-hardness testing and measurement for these specimens of
SPC test were performed. It indicates that the oxidized layer of specimens integrates and the residual
thickness of specimens increases, while the hardness of specimens increases with the increment of the
Argon flow. Moreover, the different oxidation degrees of specimens with the surface morphology
were compared in this paper. The test results show the rupture time of specimens can be effectively
prolonged by the protection of different Argon flow.